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101.
Francesco Malatesta Giovanni Antonin Paolo Sarti Beatrice Vallone Maurizio Brunori 《Biometals》1990,3(2):118-121
Summary The kinetics of electron entry in beef heart cytochromec oxidase have been studied by stopped-flow spectroscopy following chemical modification of the CuA site with mercurials. In this derivative CuA is no longer reducible by cytochrome c while cytochromea may accept electrons from the latter with rates comparable to the native enzyme. The results indicate that CuA is not the exclusive electron entry site in cytochromec oxidase. 相似文献
102.
A Rhalem C Bourdieu G Luffau P Péry 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1989,309(2):53-57
When mesenteric lymph node cells from infected mice were stimulated during an in vitro culture with exoantigens or with a purified protective antigen of Nippostrongylus brasiliensis, a drop was noted in the number of cells required to transfer protection to new mice. A maximal effect was already obtained after 4 hrs. of culture, but irradiated cells or cells from another mouse strain were unable to mediate this transfer. T cells were more effective than B cells in transferring the protection. 相似文献
103.
Nuclear pore complex assembly through the cell cycle: regulation and membrane organization 总被引:1,自引:0,他引:1
In eukaryotes, all macromolecules traffic between the nucleus and the cytoplasm through nuclear pore complexes (NPCs), which are among the largest supramolecular assemblies in cells. Although their composition in yeast and metazoa is well characterized, understanding how NPCs are assembled and form the pore through the double membrane of the nuclear envelope and how both processes are controlled still remains a challenge. Here, we summarize what is known about the biogenesis of NPCs throughout the cell cycle with special focus on the membrane reorganization and the regulation that go along with NPC assembly. 相似文献
104.
105.
Fléchon JE Kopecny V Pivko J Pavlok A Motlik J 《Reproduction, nutrition, development》2004,44(3):207-218
The zona pellucida (ZP) of mature pig oocytes is believed to consist of a dense filamentous meshwork, less compact on the inner and outer faces. The uneven surface of the ZP is made of unordered and stretched fibrils surrounding deep funnels which are the openings of the radial canaliculi. The topography of the ZP surface may contribute to the initial interplay between male and female gametes. Using cytochemical techniques for transmission electron microscopy (TEM), such as tannic acid and ruthenium red treatments, we found that the ZP of pig oocytes was essentially made of bundles of fibrils distributed in concentric layers (except in the innermost and outer parts). A correlation appears between the dense structure of the core layer of the ZP and its texture: it is constituted of superposed layers of fibril bundles, whereas only a random meshwork is found in a very thin innermost and in the outer layer. The fascicular configuration may control the permeability of the ZP, giving its semi-rigidity and elasticity, and may facilitate sperm penetration. The liquid crystal-like design of the core layer of the ZP is similar to textures found in the the vitelline envelope (zona radiata) of other vertebrates and possibly of all the deuterostomes. Such texture is probably related to the unique ZP protein composition and to a coordinated synthesis. 相似文献
106.
For detecting QTL in the whole swine genome, 1068 pigs from three F2 populations constructed by crossing European Wild boar and Pietrain (W×P), Meishan and Pietrain (M×P), and Wild Boar and
Meishan (W × M) were genotyped for genetic markers evenly spaced at approximately 20 cM intervals. AQTL analysis was performed
using a least-squares method. Here the results of the QTL analysis on the porcine chromosome 7 are presented. QTL for carcass
composition (e.g. head weight, carcass length, backfat depth, abdominal fat and bacon meat) were mapped in the chromosomal
region CYPA/CYPD-TNFB-S0102 in M×P and W×M, but not in W×P. The QTL explained 5.3%–27.2% of the F2 phenotypic variance in the two F2 populations. Most traits affected by the mapped QTL were related to carcass fatness. The mode of gene action of QTL was additive.
Surprisingly, in contrast to the parental phenotype, the QTL alleles from fatty Meishan were associated with thinner backfat
than Pietrain and Wild Boar alleles, suggesting that the genome of the fatty Meishan pig contains genes which can reduce fat
content of carcass substantially. 相似文献
107.
Koellner G Stroh A Raszewski G Holý A Bzowska A 《Nucleosides, nucleotides & nucleic acids》2003,22(5-8):1699-1702
The crystal structure at 2.05 A resolution of calf spleen PNP complexed with stoichiometric concentration of acyclic nucleoside phosphonate inhibitor, 2,6-diamino-(S)-9-[2-(phosphonomethoxy)propyl]purine, in a new space group P2(1)2(1)2(1) which contains two full trimers in the asymmetric crystal unit is described. 相似文献
108.
Richter M Ray SJ Chapman TJ Austin SJ Rebhahn J Mosmann TR Gardner H Kotelianski V deFougerolles AR Topham DJ 《Journal of immunology (Baltimore, Md. : 1950)》2007,178(7):4506-4516
Most viral infections occur in extralymphoid tissues, yet the mechanisms that regulate lymphocytes in these environments are poorly understood. One feature common to many extralymphoid environments is an abundance of extracellular matrix. We have studied the expression of two members of the beta(1) integrin family of collagen-binding receptors, alpha(1)beta(1) and alpha(2)beta(1) (CD49a, VLA-1 and CD49b, VLA-2, respectively), on CD4 and CD8 T cells during the response to influenza infection in the lung. Flow cytometry showed that whereas T cells infiltrating the lung and airways can express both CD49a and CD49b, CD49a expression was most strongly associated with the CD8+ subset. Conversely, though fewer CD4+ T cells expressed CD49a, most CD4+ cells in the lung tissue or airways expressed CD49b. This reciprocal pattern suggested that CD4 and CD8 T cells might localize differently within the lung tissue and this was supported by immunofluorescent analysis. CD8+ cells tended to localize in close proximity to the collagen IV-rich basement membranes of either the airways or blood vessels, whereas CD4+ cells tended to localize in the collagen I-rich interstitial spaces, with few in the airways. These observations suggest that CD4 T cell interaction with the tissue microenvironment is distinct from CD8 T cells and support the concept that CD4+ T cells in peripheral tissues are regulated differently than the CD8 subset. 相似文献
109.
Guillaume Holzer Paola De Magistris Cathrin Gramminger Ruchika Sachdev Adriana Magalska Allana Schooley Anja Scheufen Birgitt Lennartz Marianna TatarekNossol Hongqi Lue Monika I Linder Ulrike Kutay Christian Preisinger Daniel MorenoAndres Wolfram Antonin 《The EMBO journal》2021,40(23)
During mitotic exit, thousands of nuclear pore complexes (NPCs) assemble concomitant with the nuclear envelope to build a transport‐competent nucleus. Here, we show that Nup50 plays a crucial role in NPC assembly independent of its well‐established function in nuclear transport. RNAi‐mediated downregulation in cells or immunodepletion of Nup50 protein in Xenopus egg extracts interferes with NPC assembly. We define a conserved central region of 46 residues in Nup50 that is crucial for Nup153 and MEL28/ELYS binding, and for NPC interaction. Surprisingly, neither NPC interaction nor binding of Nup50 to importin α/β, the GTPase Ran, or chromatin is crucial for its function in the assembly process. Instead, an N‐terminal fragment of Nup50 can stimulate the Ran GTPase guanine nucleotide exchange factor RCC1 and NPC assembly, indicating that Nup50 acts via the Ran system in NPC reformation at the end of mitosis. In support of this conclusion, Nup50 mutants defective in RCC1 binding and stimulation cannot replace the wild‐type protein in in vitro NPC assembly assays, whereas excess RCC1 can compensate the loss of Nup50. 相似文献
110.
Jan Antosiewicz Beata Wielgus-Kutrowska Maciej Długosz Antonin Holy Agnieszka Bzowska 《Nucleosides, nucleotides & nucleic acids》2013,32(8-9):969-974
Complex formation of multisubstrate analogue inhibitor—2-amino-9-[2-(phosphonomethoxy)ethyl]-6-sulfanylpurine (PME-6-thio-Gua) with trimeric purine nucleoside phosphorylase from Cellulomonas sp. was investigated using a stopped-flow spectrofluorimetric approach. Results obtained indicate that, in contrast to binding of guanine, i.e., the transition-state conformation trapping ligand, for which binding at each active site is followed by the enzyme conformational change, association of the ground-state analogue PME-6-thio-Gua is a one-step process. 相似文献